It's among my favourite three of his, with the other two being Dawn and Day.
From Martin to Day, Romero was just phenomenal. Of course Night is a classic, and The Crazies is good, but he seemed to be have absolute control of his craft from Martin onwards.
He's done some good stuff post-Day, actually. Monkey Shines is darn good, and I like both Land and Diary, even if they fall short of the master's previously established standard. Looking forward to Survival, due out this March
AFAIK.